It is well known that the high carbon content of acetylene and its property of exothermically decomposing into carbon and hydrogen make it an attractive raw material for conversion to carbon and that the carbon could represent a quite cheap and good lubricating material for some industrial requirements.
A problem, which has recurrently been encountered by hollow glassware making industries, concerns the necessity that a glass gob, which is injected into a blank mold, freely passes through the blank mold in such a way that its flow is not slackened by friction with the internal walls of the mold. It may also happen that a narrow portion of the glass gob meets with difficulties during the process of loading the glass gob into the blank mold, due to a partial gob adhesion to the walls of the mold. Consequently, the temperature distribution on internal mold walls becomes substantially irregular, whereby the blanked glassware becomes irregular, too. Indeed, as the blanked glassware is transferred to the blow mold, an air flow is injected thereinto (so that the glassware is formed into a definitive shape), and the air flow acts more intensively on the bottle portions which are hotter than the others. Furthermore, the hotter portions, which are more plastic than the cooler portions, are caused to get thinner than the cooler portions, with all the apparent drawbacks.
Till not long ago, a lubricating/detaching film on the internal mold walls was manually applied by means of a brush or similar device, by spreading a mixture of oil and graphite into the mold. However, each operator did not always follow the specifications relating to the amount of mixture as well as of the frequency of such an operation, with the result that a not uniform distribution of graphite made the blanked glass not regularly cooled. Consequently the glass gob was not freely loaded into the mold. In addition, the mold would rapidly get dirty from the graphite, whereby every 8-9 hours the operation cycle required a cleaning process. Moreover, the risk for the operator, regarding possible injuries during mold lubrication, can't be forgotten. Finally, the environment was polluted by oil combustion.
For these reasons, different technological solutions were sought for, particularly solutions involving the acetylene black process, since that process is adapted to deposit a lubricating/detaching layer of carbon black on the internal mold walls. A pilot flame is provided which is able to ignite the acetylene flow at a well defined moment of the operation cycle--not during every operation cycle, but just once every n cycles--according to the specifications of glassware to be obtained. In this way, the acetylene black process is able to coat the internal walls of blank molds. However, this solution has some drawbacks, too. Indeed:
heat produced by pilot flame heats the environment around the blank mold, whereby the operator is working in difficult conditions;
the pilot flame is fed by oxygen and methane, the cost of which is nearly equal to 60% of the overall energy costs of a hollow glass forming plant;
oxygen and methane, which feed the pilot flame, are able to oxidize acetylene, whereby the carbon black which coats the internal mold walls can lose its properties which are listed in the specifications;
some portions of the blank mold are oxidized instead of lubricated by the pilot flame feeder, whereby those portions could slacken the loading process of the gob into the blank mold; sometimes the blank mold supports are blocked, due to overheating produced by pilot flame; and,
last but not least, the acetylene black process provides a collar in the bottom of the blank mold, which collar closes the bottom air-tightly, whereby the flame which is fed by acetylene is not allowed to reach the mold bottom, because it reverberates the flame, whereby not all the portions of the internal mold walls can be coated by a substantially uniform lubricating coat.
The problem which the device according to the invention intends to solve is mainly given by a solution, which allows acetylene black to arrive up to the bottom of the blank mold, in order to obtain a substantially uniform and complete coating of acetylene black on all the portions of the internal blank mold, whereby the glassware forming process can operate in a simple and correct way.